HEF’S A STUD: Jeremy Hefner has gone eight starts without allowing more than two earned runs.Getty Images

The early-season jingle of “Harvey and Niese and then they’re deceased” is a distant memory, replaced by the realization the Mets have potential depth within their starting rotation.

Matt Harvey is still an ace, but Jon Niese struggled with consistency before hitting the disabled list with a partially torn rotator cuff last month. Zack Wheeler has arrived and pitched to mixed results, but saviors have emerged in Jeremy Hefner and Dillon Gee.

It’s probably fitting Hefner will get the call for Opening Day 2 tonight when the Mets begin the second half against the Phillies at Citi Field.

Since June 4, the 27-year-old Hefner has been among the top pitchers in baseball, going 3-1 with a 1.76 ERA. He has gone eight consecutive starts without allowing more than two earned runs.

Gee, who isn’t scheduled to pitch until Monday against the Braves, is 5-1 with a 2.67 ERA since May 30.

“I’ve always been a Dillon Gee fan, I’m not surprised by him,” said an AL executive who has scouted the Mets in recent weeks. “Hefner has been a surprise. His velocity has been better, his command better and his breaking stuff more crisp. He has to be viewed as a very pleasant surprise.”

As the Mets (41-50) try to avoid a fifth straight losing season, their chances might hinge on continued excellence from Hefner and Gee.

“I think they can sustain, and I still go by the fact that I think we’re catching the ball better and therefore we’re pitching better,” manager Terry Collins said.

“You make a pitch and somebody hits it good, and we’re running it down and I think it’s made a difference. I think there’s a direct correlation, but when you’re starting to play good, you look, and if you’re pitching better you are playing better defense.”

That defensive transformation has started with the platoon of Kirk Nieuwenhuis and Juan Lagares in center field and Eric Young Jr. replacing plodding Lucas Duda in left. Omar Quintanilla has also been a dependable presence at shortstop, replacing defensively streaky Ruben Tejada.

Hefner has changed his delivery since the season started, going to a Luis Tiant approach in which he almost turns his back on the batter. Hefner credits that tweak for giving him more pop on his fastball.

“He needed that change, because he was easy to see last year,” the AL executive said. “He didn’t have much deception.”

Collins puts Hefner and Gee in the same category because both pitchers usually peak in the low 90s with their fastball — as opposed to Harvey and Wheeler, both of whom can hit the high 90s consistently.

“Those guys [Hefner and Gee], and I call them command guys, when they get on a roll they can sustain it,” Collins said. “Sometimes it takes them awhile to get command of all their stuff.

“But there is no reason they can’t continue to pitch like they are, in my opinion. I would be more concerned about the workload Harv’s got, those power guys, see how he’ll do in the middle of August.”

Collins said he’s hopeful Niese, who has begun throwing in Port St. Lucie, will rejoin the rotation in early August. Maybe the surest sign Hefner and Gee have delivered for the Mets is the fact there has been little mention of Niese in recent weeks — the team is surviving without him.

“This entire team has been about guys who have stepped up when we have asked them to,” Collins said. “It’s made a big difference.”